public class CombinatorialNumber {
	    public static void main(String args[]) {
		            int c = 0;
			            if(args.length < 1) {
					                System.out.println("Usage:java CombinatorialNumber num1 num2 ");
							            System.exit(0);
								            }
				            int tmp[] = new int[args.length];
					            for(int i=0;i<args.length;i++) {
							                tmp[i] = Integer.parseInt(args[i]);
									        }
						            if(tmp[0]<0 || tmp[1]<0 || tmp[0]<tmp[1]) {
								                System.out.println("Error!Please check your input!");
										            System.exit(0);
											            }
							            else {
									                c  = Combinatoria(tmp[0],tmp[1]);
											        }
								            System.out.println(c);
									        }
	        public static int Combinatoria(int n,int m) {
			        if(n == m || m == 0)
					            return 1;
				        else
						            return Combinatoria(n-1,m-1)+Combinatoria(n-1,m);
					    }
}
